What is the primary function of the musculoskeletal system in ultrasound imaging?
- Evaluate muscular, tendonous, and some ligamentous damage
- Assess bursitis
- Identify joint effusion
- Detect vascular pathology
- Examine soft tissue masses
- Classify masses (solid, cystic, mixed)
- Monitor post-surgical complications
- Guide injections, aspirations, or biopsies
- Assess some bony pathology
Understanding these functions is crucial for effective clinical practice.
What are the components of the musculoskeletal system anatomy that should be included in ultrasound examination?
- Tendons
- Ligaments
- Muscles
- Cartilage
- Bones
- Joints
Knowledge of these components is essential for accurate imaging and diagnosis.
What are the two forms of tendons?
- With a synovial sheath
- Without a synovial sheath
A synovial sheath has two layers and contains fluid that separates the layers.
What is the function of the bursa in the musculoskeletal system?
- Reduce friction between moving surfaces
- Facilitate movement of tendons and muscles over bones
The bursa space is typically not visible on ultrasound unless excess fluid is present.
True or false: Non-communicating bursae are found between joints, like in the shoulder.
TRUE
Communicating bursae are found in areas like the knee and can result in a baker’s cyst.
What are the four key positions for scanning the shoulder?
- Elbow bent and tucked at 90 degrees
- Elbow bent, tucked at 90 degrees and rotates out
- Hand toward back toward contralateral ‘pants pocket’
- Hand on contralateral shoulder
These positions help evaluate different structures of the shoulder.
What are the four muscles that comprise the rotator cuff?
- Subscapularis
- Supraspinatus
- Infraspinatus
- Teres Minor
The rotator cuff provides strength and stability during shoulder motion.
What is the recommended technique to correct anisotropy during MSK ultrasound scanning?
Use a heel-to-toe rocking motion to achieve a 90-degree angle
This technique helps avoid anisotropy artifacts in imaging.
What are the common artifacts seen with musculoskeletal ultrasound?
- Anisotropy
- Reverberation
- Refractile shadowing
- Time-of-flight
These artifacts can complicate the interpretation of ultrasound images.
What causes the time-of-flight artifact in musculoskeletal ultrasound imaging?
Sound waves traveling through tissues with significantly different propagation speeds
This artifact may not be easily eliminated due to tissue sound properties.
What is the normal ultrasound appearance of the biceps tendon?
Echogenic oval structure within the bicipital groove of the humerus
The biceps tendon should be ‘seated’ in the bicipital groove for normal findings.
What is the normal thickness of the biceps tendon?
Approximately 3-5 mm thick
A small amount of fluid surrounding the bicep in the bursa (less than 1.5 mm) is considered normal.
What is the role of ultrasound in evaluating the biceps tendon?
- Assess flexion and outward rotation of the forearm
- Identify tendon irregularities and surrounding fluid
The long head of the biceps tendon travels between the lesser and greater tuberosities.
What is the function of the subscapularis muscle?
Internal rotation of the arm and stabilization of the shoulder
This muscle is part of the rotator cuff and plays a key role in shoulder mechanics.
What is the responsibility of the subscapularis tendon?
- Internal rotation of the arm
- Stabilization of the shoulder joint
The subscapularis originates from the subscapular fossa and inserts onto the lesser tuberosity.
What is a unique characteristic of the subscapularis tendon?
Exhibits fibular bundles that show anisotropy
This characteristic is important for ultrasound imaging.
When scanning the subscapularis tendon, what is the patient position?
Externally rotate the arm outward with the elbow tucked in tight to the side
This position helps in visualizing the tendon effectively.
In the long axis view of the subscapularis, how should the transducer be oriented?
Notch at 9 o’clock (toward the patient’s right lateral side)
This orientation allows for proper visualization of the tendon.
What is the characteristic ultrasound appearance of the subscapularis tendon in the short axis view?
Honeycomb pattern with hyperechoic bundles and hypoechoic striations
This appearance is due to the visualization of individual tendon bundles.
What does the AC Joint attach?
- Scapula to clavicle
The AC joint serves as the main articulation that suspends the upper extremity from the trunk.
What is the normal appearance of the AC joint on ultrasound?
V-shaped hypoechoic area between the lateral clavicle and the acromion
This appearance is crucial for assessing joint health.
What should be assessed for in the AC joint during ultrasound?
- Bony irregularity
- Fluid accumulation
- Joint stability
These factors can indicate degenerative changes or traumatic injuries.
What is the function of the subacromial bursa?
Protects the underlying supraspinatus muscle from wear
It is located between the humeral head and the acromion.
What is a clinical sign of subacromial impingement during dynamic ultrasound evaluation?
Pain during shoulder abduction
This pain correlates with the movement and indicates potential impingement.
